Video compression systems are employed to reduce the number of bits needed to transmit and store a digital video signal. As a result, a lower bandwidth communication channel can be employed to transmit a compressed video signal in comparison to an uncompressed video signal. Similarly, a reduced-capacity storage device (such as a memory or a magnetic storage medium) can be employed to store a compressed video signal.
A general video compression system includes an encoder, which converts the video signal into a compressed signal, and a decoder, which reconstructs the video signal based upon the compressed signal. In applications such as video teleconferencing and television, the encoder is located remotely from the decoder, and hence, the encoder and the decoder communicate by a predetermined communication channel. In many situations, the predetermined communication channel provides a fixed bit rate of bandwidth.
Present video compression standards, such as CCITT recommendation h.261, accommodate a fixed bit rate channel by reducing a frame rate for spatially-complex scenes and for scenes having motion. Reducing the frame rate results in a decoded video signal that is best described as "jerky". Attempts have been made to fill in the missing frames by replacing frames or using linear interpolation techniques. However, the resulting video using linear interpolation is also unpleasant to view.